The present invention is directed to a vapor recovery system within a fuel dispensing environment and, more particularly, to a vapor recovery system that senses at least one environmental condition at the time of the fueling operation to accurately determine the amount of vapor being returned.
Petroleum or hydrocarbon based fueling systems have become increasingly regulated by state and federal authorities. One such regulation concerns the recovery of hydrocarbon vapor from the fuel tank of the vehicle being refueled. Absent any intervention, as fuel is introduced into the tank of the vehicle, vapor present in the tank is forced out through the filler neck and into the atmosphere. While there have been many studies as to the exact effect such emissions have on the atmosphere, the consensus appears to be, and certainly lawmakers believe, that such emissions contribute to the depletion of the ozone, may contribute to cancer rates, and are otherwise undesirable.
In response thereto, Stage II vapor recovery systems were promoted. The first systems were referred to as xe2x80x9cbalancexe2x80x9d type systems whereby an accordion like sheath encircled the nozzle of the fuel dispenser and formed a seal around the opening of the fuel tank. Simple pressure forced the vapor out of the tank and down through the sheath into the hose for recovery. Later developments included an active vapor recovery system, such as that sold by the assignee of the present invention, and as explained in U.S. Pat. No. 5,040,577, now Reissue Pat. No. No. 35,238 to Pope. The term xe2x80x9cvapor recovery systemxe2x80x9d used herein is understood to mean the Stage II systems which collect vapors during the fueling operation and direct them to a storage tank.
It is important that the vapor recovery system operates within an efficient range. If the system supplies too much vacuum during the fueling operation, the hydrocarbon vapors will be collected along with an excessive amount of air thereby over-pressurizing the underground storage tank. A relief valve on the storage tank will open at a predetermined pressure setting releasing the pressure and allowing the captured hydrocarbon vapors to escape into the environment. Conversely, an inadequate amount of vacuum prevents hydrocarbon vapors from being captured by the system at the necessary levels allowing the vapors to escape into the atmosphere at the vehicle fuel cap
Still further advancements in the field of vapor recovery led to the development of Onboard Recovery Vapor Recovery (ORVR) vehicles, wherein the vehicle itself is equipped with a vapor recovery system. A typical ORVR vehicle is explained in U.S. Pat. Nos. 4,821,908, and 5,165,379.
One of the disadvantages of the parallel development of vapor recovery is that an ORVR system may compete with the vapor recovery system of the fuel dispenser if the fuel dispenser does not have knowledge of whether the vehicle being refueled is an ORVR-equipped vehicle. In such instances, energy is wasted as both systems try to recover vapors from the fuel tank, and excessive air is pumped into the storage tank as a result of vapor recovery efforts in the face of an ORVR system.
To overcome this problem, it is advantageous that the Stage II vapor recovery system identify whether the vehicle is equipped with an ORVR system. One way to make this determination is for the vapor recovery system to measure the amount of hydrocarbon vapor being returned to the underground storage tank during the fueling operation to determine if the vehicle is recovering vapors itself (i.e. ORVR-equipped vehicle). If the vehicle is ORVR-equipped, the vapor recovery system is shut down or modified. One drawback of this determination method is the amount of hydrocarbon vapors produced during the fueling operation may vary depending upon climatic conditions. Factors such as ambient temperature, vapor temperature measured in the vapor stream as it passes through the vapor recovery passage, vehicle fuel tank temperature, and others may all affect the amount of hydrocarbons produced.
By way of example, a vehicle being driven for a length of time while the ambient temperature is about 80 degrees Fahrenheit results in a hydrocarbon concentration level of around 50-60%. In another example, the same vehicle is parked in a garage for an extended time and removed and then refueled at a nearby station where the ambient temperature is about 80 degrees Fahrenheit. Although the ambient temperature is the same as the previous example, the fuel in the vehicle""s tank may not reflect the ambient temperature and the hydrocarbon concentration is less. Therefore, even if the ambient temperature is at a value of about 80 degrees Fahrenheit it may not equate to a higher hydrocarbon level. In another example, many fuel injected vehicles will have a higher fuel/vapor temperature due to the fuel being recirculated from the injection pump back to the fuel tank itself.
Therefore, there is a need for a vapor recovery system that may receive various inputs that may affect an expected hydrocarbon threshold level. The calculated expected hydrocarbon threshold level that can then be compared to the actual amount of hydrocarbon vapor produced during the fueling operation. This comparison determines whether the vehicle is equipped with an ORVR system.
The present invention is directed to a system and method of determining whether a vehicle is equipped with an onboard recovery vapor recovery system. The invention determines a threshold vapor concentration level and senses environmental conditions during the fueling process to determine and varies the threshold level upwards or downwards. Additionally, an actual amount of hydrocarbon vapor is sensed. The two values are compared, and the vehicle is calculated to have an ORVR system if the actual value is below the adjusted threshold amount by a predetermined range.
In one embodiment, the method includes determining a fuel flow and a threshold vapor concentration. Environmental conditions are received from sensors at the fueling operation, and the threshold vapor concentration is adjusted upward or downward dependent upon the environmental conditions. The actual vapor concentration within the vapor recovery passage is sensed. Finally, the two values are compared to determine whether the vehicle is equipped with an onboard recovery vapor recovery system.
Within this embodiment, the threshold vapor concentration may be predetermined and based on tested results. Additionally, different types of vapor sensors may sense the actual vapor concentration within the vapor recovery passage. Sensors may include indirect or direct sensors.
A processor may be positioned within the fueling system for receiving signals from the various input devices and making calculations on whether the vehicle is equipped with an ORVR system. The processor may include a memory with look-up tables, or may be programmed to compute values based on predetermined mathematical formulas.